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Patented Dec. 22, 3953 PROCESS ZFOR EIMPRUVJNG ALCQHOL QUALITY Samuel W.Wilson and Elaine 1T. Delaune, Baton Rouge, La., assignors tostandard'oilDevelopment Company, a corporatiomof 'Delaware .No Drawing.:Application Jnne.-1r3,.195.(l, vHSeriaLNo. 167,916

.grcldims. -(Cl. 210-122) This invention relates to the, purification oftalcohols and aqueous solutions thereof and particularly to the removaltherefrom of malo'dorous impurities.

It is Well known that the substantially watersoluble alcohols containing1 'to.5 carbon atoms per molecule and particularly those prepared ':bythe acid catalyzed'hydration of mono-'olefinsare often contaminated withmaterials 'which give rise to distinct unpleasant odors whichrend'ertthefinal pro-duct unsaleable or at least limit its'marketability. The aboveis especially true 'o'fthose alcohols prepared'loy the sulfuricacid-catalyzed hydration of olefins which process is presently incommercial operation in the preparation of ethanol and isopropanol fromethylene and propylene respectively.

It has now been found that alcohol corrtaminated by malodorous compoundsis deodorized by intimately contacting the alcohol or its aqueoussolution with finely-divided sand. River sand, blasting sand, gravelsuchas pea gravland Ottawasand etcgare particularly effective. "The sandemployed is preferably'one of not-finer than 30 mesh particle size.Particle sizes above '30 mesh are operable but are not "as satisfactory.Particle sizes of A-TZOmesh are preferred, although coarser materialmaybe used. The-sand'requires no preliminary .treatmen'trprior to .its use.Although the sands named have been found to be effective in removingmalodorous materials from alcohols, other solid adsorbents of a similarnature such as silica gel, silicic acid, diatomaceous silica, andasbestos produce no improvement whatsoever in the quality of thealcohol.

The odors associated with the alcohols, especially those prepared by thesulfuric acidscatalyzed hydration of mono-olefins are of two distincttypes. The first has been-called inthetracle recycle odor. This odor isusually a lightingitive odor associated with low-boiling sulfurcompounds such as mercaptans, thio-aldehydes, etc. It is believed thatthese low boiling sulfur compounds result from .the decomposition of ahigher boiling parent compound releasing .the sulfur compound-and inaddition-a hydrocarbon.

Therefore, a hydrocarbon odor is usually always achieved in a continuousmanner.

2 with sand completely .removes the recycle .odor and in all casesdiminishes the intensity of the butyl'otlor.

'The intimate contact of the odoriferous alcohol with the "finelydivided sand is "carried out with the alcohol either in theliquidphaseor in the vapor p'ha'se. However, liquid phase treatmentis preferred. Inconducting"the 'liquidphase contacting two methods are-preferablyemployed,

namely, --gravity flow of.alc o-hol through a bed ofsand, -or, .upfiowpassage of the liquid alcohol under pump pressure through the :bedofsand. However, it 'is also possible to mix the alcohol and the sand byagitation and thereafter separate the alcohol from the mixture bypassage through a filter press or by settling and decantati-on. However,this method is not preferred to "the passage or the liquid alcoholthrough a bed of sand which may be more satisfactorily If a vapor:phase-:.operation is desired .theealcohol is heated "aboveits boiling;point and the vapors are percolated through a body of the sand.

vIn case of incompleteremoval :of :theimalodor- D materials theirateofflow ofzthe liquidtthrough the sand 'sbeil maybe decreased, the depthor the "number 'of the beds may be increased, and/or :passage of thealcoholethrdug'h:thegsand may be repeated. The rate of now .throughtthe.bed can be fixed at a figure of 0.5 to 50 volumes of alcohol per volumeof sand per hour. Generally a rate of 2-20 v./v./hr..is. preferred.

The mechanism of -the operationuwhereby the odor is removed is notknown. However, it has been established that the sand not only removesthe malodorous impurities from the alcohol but also removes reducingsubstances. Alcohols filtered through a bed of sand show a decided im--=prov.ement in -;p.ern1anganate time which is a .measure of thereducing substances present. Recycle odor may/"possibly be due to thepresence of fireducingzsubstances. But in addition the ".butylodor ofthe: alcohol is also-improved and the -materials-gi-vingriseto-butyl-odonarenot neces- 'TSHJIiIy reducing materials. Thepermanganate itime employed iii-testing the treated alcohols is timeUSPamethod whichis ameasureofgthe time .iniminutes for 0.1 cc. of an-0.1"il l solution of 3KMI104 at 15 C..to.fa.de.-fromza lightpink color.The lower the permanganate time inminutes the poorer the quality of thealcohol indicating the presence therein of reducing -materials.

Up to the present time*it*has-=not'been found necessary to carry .outany regeneration of the sand since 's-no harmful effect has ---'beenobserved by continuous treatment of the alcohol with the sand. During apresent period of 40 days continuous operation, approximately 1 milliongallons of off-odor isopropanol has been deodorized by filtering througha sand bed. The sand is still in perfect operating condition. It hasbeen found further that an alcohol of extremely poor quality withrespect to odor can be passed through the bed of sand and a decidedlyimproved alcohol recovered therefrom. Immediately thereafter a morerefined, less malodorous alcohol can be passed through the same bed andit too is upgraded in its quality, particularly its odor. It iscontemplated that the sand when necessary can be revivified by simpleoperation such as Waterwashing, aeration or mere movement of the sandwithin the bed. Regeneration is not an important factor because of thecheapness and ready availability of the sand.

It has also been found that the shape and sharpness of the sandparticles has no critical effect on the activity of the sand. Blastingsand which is particularly rough and sharp, and Ottawa sand which isextremely smooth and round both give effective results.

It has been found that sand will upgrade any malodorous alcoholwhatsoever regardless of the state of its refinement. Even a goodalcohol reacts favorably. The alcohol after passage through the sandneeds no further treatment and is sent directly to storage. In thetables to follow setting forth the results of experimental work,alcohols are graded as follows:

Grade 1, alcohol with no foreign odor;

Grade 2, an alcohol with a very slight foreign odor;

Grade 3, an alcohol with a moderately noticeable odor;

Grade 4, an alcohol containing appreciable to excessive amounts of odor.

The effectiveness of sands in removing both recycle and butyl odors fromalcohols is shown in the following tables. In Table I, the upgrading ofa highly malodorous alcohol contaminated with both recycle andhydrocarbon odors are set forth. In Table II data are given for thetreatment of a less malodorous alcohol contaminated with both recycleand hydrocarbon odors, while in Table III the data are shown on thetreatment of an alcohol highly contaminated with butyl odor.

Similar results were obtained of the treatment of ethanol by intimatecontact with finely divided sands. These data are shown in Table IV.

The data in Table V demonstrates the effectiveness of the sands inimproving the permanganate time of the alcohols treated.

Equally good results have also been obtained by aerating the sand bedduring passage of the alcohol therethrough. This is accomplished bybubbling air, nitrogen or other inert, non-reactive gas through the sandbed simultaneously with the passage of the alcohol.

TABLE I Effect of sands on removing recycle odor from isopropanolQuantity of Alcohol brfore Alcohol after Packing alcohol, ml. contactcontact Remarks River sand 3- 8 2, 00 4 r and H0..- 3H0, no rec Definiteodor 1 rovement Blasting sand 6-12 0 (1 p Ship island sand 8 6-18 Do.

Ottawa sand. 1 Do.

Pea gravel." 6-18 Do.

silica gel -1 No improvement.

Acid silicic (SiO2.XHzO) 6 Do Dicalite (diatomaceous s1l1ca) 6 DAsbestos Quite sour odor; odor may be masked; no improvement.

*Rec.= Recycle odor.

HO =Hydrocarbon odor.

==Louisiana sharp particle sand.

TABLE II E fiect of sands on removing recycle and hydrocarbon odor fromisopropcmol Quantity of Alcohol before Alcohol after Packing alcohol,ml. contact* contact Remarks River sand 200 3 and 2 HC I10 I60 Definiteodor im rovement Blasting sand 12-15 0 D o. P

Ship island sand 12-15 D 0.

Ottawa sand.-. 12-15 DO.

Pea gravel. Do.

Silica gel N0 improvement.

Dicalite (diatomaceous si11ca).- 6 D0.

Asbestos Quite i011! odor; no improvenicn *Rec.= Recycle odor. HGHydrocarbon odor. e =Louisiana sharp particle sand.

TABLE 1 -Efiect raj-sanction rem-bein butyliidor ifrb'm isop'rop'cmbl pQuantity Alcohol meager f N Q Packing v./v./hr of alcohol, before after.Remarks ml. contact contact River sand 9-18 1, 200 4 butyl 3 butylm.Definite odor improvement. Blasting sand 6-18 1,200 -do do *Do. Shipisland sand 9-18 Do. Ottawa sand 9-18 Do. Pea gravel" 12-18 Do. Silicagel 3-18 N'o' improvement. Acid silicic (SiO2.XH2O 6 Do. Dicalite(diatomaceous si] 6 Do. Asbestos 6-18 Sour odor; butyl odor strong;

no improvement.

Louisiana sharp particle sand.

TABLE IV Effect of sands on removing malodor from ethanol QuantityPacking v./v./hr 11111 1211001- Alcohol before contact Alcohol aftercontact River sand 3-18 1,500 Recycle type odor; No recycle odor; verygood smelling;

poor smelling. better than standard. Blasting sand. 3-18 1, 500 d Do.Ship island san 3-18 1, 500 Do. Ottawa sand 3-18 1, 500 Do. Pea graveL3-18 1, 500 D0. Silica gel 3-18 1, 500 No improvement. Acid silicic(S102. XHzO) 6-12 300 D0. Dicalite (diatomaceous silica) 6-12 300 Do.Asbestos 6-18 300 D0.

TABLE V Efiect of sands in improving the permanganate time of alcoholsBefore contact, odor perman- After contact, odor er- Alcohol Contactagent ganate time manganate time 1 B] t d 4 B t 1 3 b t 1 or) Iso rolacohol as ing san u y u y B5? o 3 l5 2H0 70 HO-No rec 60 10 2 acetate90 Recycle type odor, 2 No recycle 90 poor smelling.

What is claimed is:

1. A process for improving the odor characteristics of a Water-solublealcohol contaminated by high-boiling hydrocarbon and sulfur compoundswhich make the alcohol malodorous and which is prepared by hydration ofa mono-olefin, which comprises intimately contacting the contaminatedmalodorous alcohol with sand in the absence of other purifying agents ata space velocity in the range of 0.5 to volumes of the alcohol pervolume of sand per hour, whereby the alcohol is rendered substantiallyless malodorous.

2. A process according to claim 1, in which a stream of the malodorousalcohol is passed in liquid phase into a bed of the sand for intimatelycontacting therewith, and in which the resulting alcohol renderedsubstantially less malodorous is passed through the bed of sand.

3. A process according to claim 1, in which the malodorous alcohol is invapor phase when intimately contacted with the sand.

4. A process for improving the odor characteristics of a malodorousisopropanol contaminated by high-boiling hydrocarbon and sulfurcompounds which are odoriferous and'which is prepared by hydration ofpropylene, which comprises intimately contacting the malodorousisopropanol in the liquid phase with sand at a rate of flow of 0.5 to 50volumes of the alcohol per volume of the sand per hour in the absence ofother purifying agents, whereby the iscpropanol is renderedsubstantially less malodorous, and withdrawing the isopropanol renderedsubstantially less malodorous from the sand.

5. A process according to claim 4, in which the sand is of 4 to 30 meshparticle size.

6. A process according to claim 4 in which a stream of the malodorousisopropanol in liquid phase is passed upwardly through a bed of the sandfor intimately contacting the malodorous isopropanol with the sand.

'7. A process for improving the odor characteristics of malodorousethanol contaminated by high-boiling hydrocarbon and sulfur compoundswhich are malodorous and which is prepared by hydration of ethylene,which comprises intimately contacting the malodorous ethanol in theliquid phase with sand at a rate of now of 0.5 to 50 volumes of thealcohol per volume of the sand per hour in the absence of otherpurifying agents, whereby the ethanol is rendered substantially lessmalodorous and withdrawing said enthanol substantially less malodorousfrom the sand.

8. A process according to claim 7 in which the sand is 4 to 30 meshparticle size.

7 9. A process according to claim 7 in which a Number stream ofmalodorous ethanol in the liquid phase 159,450 is passed upwardlythrough a bed of the sand for 161,642 intimately contacting themalodorous ethanol 1,162,212 with the sand. 5 2,546,650

SAMUEL W. WILSON. ELAINE T. DELAUNE.

Number References Cited in the file of this patent 7 7 UNITED STATESPATENTS 10 Number Name Date 56,863 Prentiss et al July 31, 1866 NameDate Reford Feb. 2, 1875 Spier Apr. 6, 1875 Bloom Nov. 30, 1915 NijbaerMar. 27, 1951 FOREIGN PATENTS Country Date Great Britain of 1855

1. A PROCESS FOR IMPROVING THE ODOR CHARACTERISTICS OF A WATER-SOLUBLEALCOHOL CONTAMINATED BY HIGH-BOILING HYDROCARBON AND SULFUR COMPOUNDSWHICH MAKE THE ALCOHOL MALODOROUS AND WHICH IS PREPARED BY HYDRATION OFA MONO-OLEFIN, WHICH COMPRISES INTIMATELY CONTACTING THE CONTAMINATEDMALODOROUS ALCOHOL WITH SAND IN THE ABSENCE OF OTHER PURIFYING AGENTS ATA SPACE VELOCITY IN THE RANGE OF 0.5 TO 50 VOLUMES OF THE ALCOHOL PERVOLUME OF SAND PER HOUR, WHEREBY THE ALCOHOL IS RENDERED SUBSTANTIALLYLESS MALODOROUS.